I think there's been posts that the sample file is outdated and has glitches. So, if you're getting errors back from Roku about it that may be while.
Otherwise, if you're asking how to customize it to your own channel, just take out the current names, urls etc and swap in your own. Be very careful of the comma's, as they signal more related info is coming, whereas no comma means hard stop on that topic. Sorry if that doesn't answer your question, the post was a bit vague.